Defence behaviour of reindeer in response to flying parasitic Diptera

Similar defence behaviours were exhibited by a reindeer when experimentally exposed to three different species of tethered, flying parasitic Diptera, Cephenemyia trompe (Modeer), Hypoderma tarandi (L) and Tabanid. Defencive behavioural responses appeared to be related to attack angle, and were not elicited by auditory stimuli. These observations raise questions about the validity of parasite species-specific defence responses in reindeer.Forsvars-adferd hos rein angrepet av flyvende, parasittiske diptera.Abstract in Norwegian / Sammendrag: Likeartet forsvars-adferd ble utvist av en rein som ble eksperimentelt utsatt for tre forskjellige arter av bundne, flyvende parasittiske diptera, Cephenemyia trompe (Modeer), Hypoderma tarandi (L) og Tabanid. Den forsvarsmessige adferd syntes å ha sammenheng med parasittenes angreps-vinkel og ble ikke utløst av lydstimuli. Disse observasjoner reiser spørsmål om gyldigheten av parasittære artsspesifikke forsvarsreaksjoner hos rein.Poron puolustuskàyttàytyminen lentàvià kaksisiipisià (Diptera) hyônteisià vastaan.Abstract in Finnish / Yhteenveto: Poro kàyttàytyi samalla tavalla kun se joutui tekemisiin kolmen kiinniolevan lentàvân kaksisiipisen hyônteisen: saulakan {Cephenemyia trompe Modeer), kurumupaarman {Hypoderma tarandi L) ja parman kanssa. Puolustuskàyttàytyminen riippui hyônteisen làhestymiskulvàt kysymyksià lajispesifisen puolustuskàyttàytymisen esiintymisestà proolla hyônteisià vastaan

Effects of ovarian fluid on sperm velocity in Arctic charr ( Salvelinus alpinus )

Numbers of studies in externally fertilizing fish species provide evidence for an effect of ovarian fluid on sperm motility characteristics such as duration of forward mobility, velocity or percent motile sperm cells. Yet, because of variations among females in the quality of their ovarian fluid, such effects might differ between individuals. Additionally, ovarian fluid from different females could also be expected to affect each ejaculate differently, resulting in cryptic female choice. In this study on Artic charr (Salvelnius alpinus), sperm velocity from several males was measured in the diluted ovarian fluid of several females according to a fully balanced crossing design. This design allowed us to estimate variations among females in the effect of their ovarian fluid on the velocity of sperm from different males, and to detect variations among males in the ability of their sperm to swim in ovarian fluid. Sperm velocity was estimated by computer-assisted sperm analysis. Average velocity was found to vary among females, with some females having constantly higher velocity measurements in their ovarian fluid, and among males, indicating that some males had overall faster sperm in ovarian fluid than others. Moreover, variation in sperm velocity was shown to depend on individual female-male interactions. Our results document that females vary in the effect of their ovarian fluid on sperm velocity and that their ovarian fluid may stimulate sperm velocity according to individual characteristics of males. This latter result suggests a potential mechanism for cryptic female choic

Own,but not foreign seminal fluid inhibits sperm activation in a vertebrate with external fertilization

This Document is Protected by copyright and was first published by Frontiers. All rights reserved. It is reproduced with permission.Seminal fluids are known to have a variety of effects on rival sperm, but in externally fertilizing species it is still unclear what effects seminal fluid can induce under sperm competition. We recorded sperm activity from natural ejaculates (including own seminal fluid) of an external fertilizer, the Arctic charr (Salvelinus alpinus), after activation either in water (the natural medium for milt dilution), in a dilution of water and own seminal fluid or in a dilution of water and seminal fluid of a foreign male. When activation occurred in own or foreign dilutions of seminal fluids, sperm maintained higher velocities than when activated in water only. Yet, velocity did not differ depending on whether sperm was activated in own or foreign seminal fluid solutions. More important, approximately 25% fewer sperm cells were initially activated in own seminal fluid than in foreign seminal fluid or water, indicating that activation is under close control of own seminal fluid only. Our results document that the presence of foreign seminal fluid under sperm competition do not have apparent effect on sperm velocity. Yet, the large inhibitory effect on initial activation of sperm cells seen in own, but not in foreign dilutions of seminal fluids (and water) suggests an individual specific recognition mechanism exerted by something in the seminal fluid on own, but not foreign sperm cells. The importance of this extrasomatic sperm recognition for the outcome of sperm competitions is discussed

Resemblance Reporting on Children: Sisters Are More Proactive than Brothers

The asymmetric grandparental investment in humans may ultimately be explained by the paternity uncertainty hypothesis. The proximate mechanisms leading to grandparental bias in investment in grandchildren are, however, unclear. In a study of 233 males and females with an opposite sexed sibling, we examined whether comments on resemblance regarding one’s own child, or one’s sibling’s child, changed in frequency after both siblings became parents. We found that comments among siblings on resemblance of children occurred more frequently after both became parents, compared to when only one of the siblings had children, suggesting that resemblance descriptions may become more important after both siblings have children. Furthermore, and in line with the suggestion that mothers may mentally exploit the alloparenting environment by holding a stronger belief about resemblance, brothers reported that their sisters commented on resemblance concerning their own child more often and more intensely. Additionally, sisters corroborated this fnding by self-reporting that they were the most proactive during resemblance descriptions of their brothers’ child. Thus, sisters might, through more frequent voicing of stronger opinions on parent–child resemblance than their brothers, infuence alloparents’ perception of resemblance to their children and thus infuence alloparental investments. Communicating resemblance · Paternal uncertainty · Sex differences · Phenotypic resemblance · Grandparental investment · Manipulative mother hypothesi

Cannibalism and protective behavior of eggs in Arctic charr (Salvelinus alpinus)

From video recordings of spawning events, we quantified protective and cannibalistic behavior of Arctic charr occurring immediately after spawning. The number of fish cannibalizing on stray eggs was examined regarding (a) whether more than one male shed milt during the spawning event, that is, whether sperm competition occurred, (b) whether the sperm competition included few or many males, that is, the intensity of sperm competition, and (c) the density of fish at the spawning site. Response behavior toward egg cannibalism was also examined among females and dominant males in order to determine any parental investment toward protecting the eggs after spawning. Cannibalistic behavior was seen in almost 50% of the spawnings, and the multiple spawning events showed the highest numbers of fish cannibalizing on eggs. Both the number of males releasing milt and the number of fish approaching the spawning site were positively correlated with egg cannibalism. Sperm competition was, however, not a prerequisite for egg cannibalism. Although we also observed partial filial cannibalism, protective behavior of eggs was seen both among dominant males and females, suggesting that charr actually conduct parental care.publishedVersio

Status specific tailoring of sperm behavior in an external fertilizer

Published version. Source at https://doi.org/10.3389/fevo.2016.00135 Why dominant males experiencing intense sperm competition sometimes show low investments in sperm production is not always obvious. One well-documented example is that of the external fertilizing teleost, the Arctic charr (Salvelinus alpinus), where individuals becoming dominant reduce sperm production and sperm swimming speed in water compared to subordinates. Here, we report how ovarian fluid differentially influences sperm velocity of dominant and subordinate male Arctic charr. That is, sperm from dominant males increase their velocity in water diluted ovarian fluid compared to that observed in water, while sperm from subordinates, on the other hand, decrease velocity in ovarian fluid compared to that observed in water. Thus, subordinates, who invest more resources in their sperm and usually show the highest sperm velocity in water, have lower gains from their investment than dominant males when sperm are swimming in ovarian fluid. In sum, our result suggests that ovarian fluid increase sperm velocity more in dominant males than in subordinate males. Although this finding could partly be caused by cryptic female choice exerted by the ovarian fluid for sperm from dominant males, an alternative and more parsimonious explanation is that sperm from dominant males may simply be better designed for swimming in ovarian fluid compared to sperm from subordinate males. Thus, sperm production in the two reproductive roles seems to be adaptively tailored to different external environments

Do mothers also “manipulate” grandparental care?

Paternity uncertainty has proven to be a robust ultimate hypothesis for predicting the higher investment in grandchildren observed among maternal grandparents compared to that of the paternal grandparents. Yet the proximate mechanisms for generating such preferred biases in grandparental investment remain unclear. Here we address two different questions for better understanding the proximate mechanisms leading to the observed bias in grandparental investments: (i) is there a larger emphasis on resemblance descriptions (between grandchildren and grandparent) among daughters than among sons, and (ii) do mothers really believe that their offspring more resemble their parents, that is, the children’s grandparents, than fathers do? From questioning grandparents, we find that daughters more often and more intensely than sons express opinions about grandchild–grandparent resemblance. Moreover, daughters also seem to believe that their children more resemble their grandmother than sons do. The latter is, however, not the case for beliefs about children’s resemblance to grandfathers. In sum, our results suggest that even in a population of Norwegians, strongly influenced by ideas concerning gender equality, there exist a sexual bias among parents in opinions and descriptions about grandchild–grandparent resemblance. This resemblance bias, which echoes that of mothers biasing resemblance descriptions of newborns to putative fathers, does not seem to represent a conscious manipulation. Yet it could be instrumental for influencing grandparental investments. We believe that a “manipulative mother hypothesis” might parsimoniously account for many of the results relating to biased alloparenting hitherto not entirely explained by “the paternity uncertainty hypothesis.